1. Field of the Invention
The present invention pertains to a forehead pad and forehead support pad for use in a forehead support portion of a patient interface device, such as a nasal or full face mask.
2. Description of the Related Art
There are numerous situations where it is necessary or desirable to deliver a flow of breathing gas non-invasively to the airway of a patient, i.e., without intubating the patient or surgically inserting a tracheal tube in their esophagus. For example, it is known to ventilate a patient using a technique known as non-invasive ventilation. It is also known to deliver continuous positive airway pressure (CPAP) or variable airway pressure, which varies with the patient's respiratory cycle or with the condition of the patient (auto-titration pressure support systems), to treat a medical disorder, such as sleep apnea syndrome, in particular, obstructive sleep apnea (OSA) or congestive heart failure.
Non-invasive ventilation and pressure support therapies involve the placement of a patient interface device, which is typically a nasal or nasal/oral mask, on the face of a patient to interface the ventilator or pressure support device with the airway of the patient so that a flow of breathing gas can be delivered from the pressure/flow generating device to the airway of the patient. Because such masks are typically worn for an extended period of time, it is important the mask fit properly and comfortably on the patient. This is made difficult in that in order for the mask to maintain a seal without any undue gas leaks around the periphery of the mask, the mask may be compressed against the patient's face.
It is known to provide forehead supports associated with gas delivery masks to provide a support mechanism between the mask and the patient's forehead. Gas delivery masks having forehead cushions, spacers or supports are described in U.S. Pat. Nos. 4,907,584; 5,243,971; 5,570,689; 6,119,693; 6,357,441; 6,463,931; 6,467,483; 6,520,182; 6,532,961; 6,557,556. The forehead supports prevent the mask from exerting too much force on a patient's face and provides stability to the mask.
The forehead support devices in the above-identified patents typically have at least one forehead pad attached to the forehead support. The forehead pad contacts the surface of the patient. In U.S. Pat. Nos. 4,907,584; 5,243,971; 5,517,986, 5,570,689, and 6,357,441 the forehead support pads typically made of foam and have a generally rectangular or trapezoidal in shape with relatively sharp edges. The conventional forehead pads taught in U.S. Pat. Nos. 6,119,693; 6,463,931; 6,467,483; 6,520,182; 6,532,961; and 6,557,556 have a semi-circular profile to compensate for any angular variation between the forehead support structure and the surface of the patient. The disadvantage of that is the pad rests on the forehead on a curved surface which translates into pressure point. These semi-circular designs allow the curved contact to compress and deform to secure a flatter contact. Again, that creates pressure points and it is not the most comfortable option.
The product literature for the MAP Papillon mask shows a forehead pad that attaches to the forehead support via a stem. The stem and/or the attachment of the stem to the forehead support frame allows for some articulation of the main portion of the forehead pad. However, the relatively small size of the stem provides a relatively unstable platform for mounting the forehead pad on the support frame.